#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	cin >> n;
	int result=n;
	for(int i=0;i*11<=n;i++)
	{
		int remaining = n - i * 11;
        int pieces = i;
        pieces += remaining / 5;
        remaining %= 5;
        pieces += remaining;
        result = min(result, pieces);
	}
	cout << result ;
	return 0;
}